This invention relates to an automatic injection device, in particular for andrological use.
Automatic injection devices for self-administered drug therapies are currently known, especially for the treatment of erection disorders, where injection devices similar to pens are used to enable patients to self-inject vasoactive drugs directly into the cavernosum, in an extremely safe and simple manner.
Injection devices of the above mentioned type are the subject of previous patents and patent applications. The automatic injection device of U.S. Pat. No. 4,316,463 by William L. Schmitz comprises a barrel inside which there is a charged ampoule associated with a plunger and a needle. When the plunger is depressed the ampoule thrusts forward on the needle, which simultaneously projects from the barrel.
A similar technique is employed in the German model G 8333 718.0.
The automatic injection device of European patent 92304953.0 by Owen Munford Ltd employs a spring loaded drive member which thrusts forward on a charged capsule and a needle associated with the capsule, the needle projects from the device injects the drug and immediately after returns to the retracted position inside the device.
The injection device of European patent 87116619.5 by Wilhelm Haselmeier GmbH comprises a barrel housing a charged syringe, whose plunger is thrust forward by a piston depressed by a cylindrical body.
The injection device of Italian patent application RM92 A 000881 employs a spring loaded drive member which thrusts forward on the plunger of a charged syringe housed inside the device and ejects the drug through the needle.
The above mentioned injection devices feature several common characteristics, such as the barrel housing, a generally spring loaded internal mechanism, which, when activated, thrusts forward on the plunger of a charged syringe or capsule. Unfortunately, these injection devices also feature shortcomings which may be especially uncomfortable for the patient, such as an excessive bulkiness, especially with regard to the length; the impossibility to regulate the force of the spring loaded drive member which, when released, thrusts forward on the syringe plunger and the needle; the impossibility to regulate the length of the needle projecting from the device; the stability of the needle, which is not always guaranteed; and, last but not least, the excessive bulkiness of the injection devices which are currently available, to the detriment of what should be one of the key advantages of these devices: discretion.